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Law enforcement agencies across the UK effectively campaigned to deploy a face scanning system known to be discriminatory against women, young people, and individuals from ethnic minority groups, following complaints that a less biased version produced fewer investigative leads.

The Technology in Practice

UK forces utilize the police national database (PND) to carry out retrospective facial recognition searches. This procedure entails matching a “probe image” of a person of interest against a database of more than 19 million custody photos to find possible hits.

Acknowledged Discrimination

The UK interior ministry conceded last week that the system was biased. This admission came after a study by the National Physical Laboratory (NPL) determined it incorrectly matched Black and Asian people and women at significantly higher rates than white men. The ministry said it “took steps on the findings”.

“This raises the question of whether facial recognition only becomes effective if users tolerate biases in ethnicity and sex. Convenience is a poor argument for disregarding fundamental rights.”

Known Issue

Internal documents show that this discriminatory flaw has been known about for over twelve months. Furthermore, police forces lobbied to reverse an initial decision that was designed to address the problem.

Police bosses were notified of the system's bias in September 2024. The government-ordered NPL review concluded the system was more likely to produce false positives for photos of women, Black people, and those under 40 years old.

A Reversed Decision

In response, the National Police Chiefs’ Council (NPCC) mandated that the accuracy setting required for possible hits be increased to a point where the disparity was significantly reduced.

However, this directive was reversed the following month after forces complained that the adjusted system was producing fewer “investigative leads”. Internal records indicate the higher threshold cut the proportion of searches resulting in possible identifications from over half to a just under 15%.

Profound Inequalities

Although the authorities declined to specify what threshold is now in operation, the latest independent review found the system could generate incorrect matches for women of Black heritage almost 100 times more often than for white women at certain settings.

The ministry stated on these findings: “Our evaluation found that in a specific scenarios the software is more likely to incorrectly include some demographic groups in its match reports.”

Balancing Utility and Fairness

Outlining the effect of the temporary raise to the system's accuracy setting, the NPCC documents note: “This adjustment greatly lessens the effect of bias across protected characteristics of race, age and gender but had a substantially detrimental effect on police efficiency”. The documents further note that forces argued that “a once effective tactic returned results of limited benefit”.

Wider Implementation Proposals

Meanwhile, the government has launched a two-and-a-half-month public review on its proposals to widen the use of biometric scanning systems. Policing minister Sarah Jones has labeled the technology as the “most significant advance since DNA matching”.

Criticism from Advisors and Monitors

Abimbola Johnson, chair of the advisory panel for the police race action plan, commented: “We observed scant discussion through equality strategy sessions of the facial recognition rollout despite clear relevance with the plan’s concerns.

“These revelations show once again that the pledges to combat discrimination policing has undertaken via the equality initiative are not being translated into broader operations. Our reports have cautioned that innovative tools are being rolled out in a context where racial disparities, inadequate oversight and faulty information gathering continue to exist.

“Any use of facial recognition must meet rigorous official guidelines, be independently scrutinised, and demonstrate it diminishes rather than compounds racial disparity.”

Official Statement

A Home Office spokesperson stated: “We takes the findings of the study with utmost gravity and we have implemented changes. A updated software has been externally evaluated and acquired, which has no statistically significant bias. It will be tested early next year and will be undergo further assessment.

“The foremost aim is ensuring public safety. This revolutionary tool will assist police to put criminals and rapists behind bars. There is human involvement in each stage of the procedure and no arrest or charge would be pursued without trained officers meticulously examining the output.”